Field of the Invention
This invention relates to a color wheel component which can control the color or direction of output light.
Description of the Related Art
To provide high power, high brightness projection light, current projectors are moving toward using light sources based on wavelength conversion principles. In this type of light sources, using wavelength conversion wheel devices have the advantage of extended life and enhanced light conversion efficiency.
Current wavelength conversion wheel devices typically include a motor and a wavelength conversion wheel. Based on the light travelling direction on the wavelength conversion wheel, wavelength conversion wheel devices fall into two main categories.
The first category uses transmission type wavelength conversion wheels. As shown in FIG. 1, the wavelength conversion wheel device includes a motor 1, and a wavelength conversion wheel 2 having a stacked multi-layer structure: dichroic reflector 22, wavelength conversion material layer 21 and filter plate 23. To save materials, the wavelength conversion material 211 on the wavelength conversion material layer 21 has a ring shaped distribution, where the area 212 inside the ring or an area outside of the ring does not carry any wavelength conversion materials because it is not in the illumination path of the excitation light. The working principle of this type of wavelength conversion wheel is illustrated in FIG. 2. The excitation light 4 passes through the dichroic reflector 22 to illuminate the wavelength conversion material layer 21. The wavelength conversion material generates a converted light in all directions. The converted light traveling toward the filter 23 will pass through the filter 23 to become the output light 51 of the light source device; the converted light 50 traveling toward the dichroic reflector 22 will be partially reflected by the reflecting face 221 back to the wavelength conversion material layer 21. Another part of the converted light (e.g. 52) will pass through the dichroic reflector 22 and become lost.
The second category uses reflection type wavelength conversion wheels. As shown in FIG. 3, the wavelength conversion wheel device includes a motor 1, and a wavelength conversion wheel 2 having a stacked multi-layer structure: reflector 24 (such as but is not limited to metal reflector plates), and wavelength conversion material layer 21. The working principle of this type of wavelength conversion wheel is as follows. The excitation light illuminates the wavelength conversion material layer 21; a part of the excitation light that is not absorbed by the wavelength conversion material will be reflected by the reflector 24 back to the wavelength conversion material layer 21. The converted light generated by the wavelength conversion material travels in all directions. Of the converted light traveling toward the reflector 24, a major portion will be reflected by the reflector 24 back to the wavelength conversion material layer 21; a minor portion of the converted light will be absorbed by the reflector 24 and become lost.
A problem with the above two types of conventional devices is that in both the transmission type and the reflection type wavelength conversion wheel devices, a part of the converted light is lost. This adversely affects the output brightness of the light source device. In particular, for the transmission type device, because the wavelength conversion material layer 21 directly contacts the filter 23, converted light 51 that exits at large angles will increase the output light spot size of the light source device.